2012
«Dos per dos són mil». Available in English “Two plus two equals one thousand”, by Antràs, P. and Ventura, J. http://www.wilson.cat/en/comunicats-conjunts/item/215-dos-m%C3%A9s-dos-s%C3%B3n-mil-els-efectes-comercials-de-la-independ%C3%A8ncia.htmlExtract (Conclusion 12): "...in the worst-case scenario, sales would drop 18%, and a price drop of
40 + 10 = 50% would be necessary to reallocate the sales. Under such as
pessimistic scenario, the fall in Catalan GDP would be 0.18 x 0.5 x 22.5
= 2.0%. For the more plausible price reduction of 25 + 10 = 35%, the
fall in Catalan GDP would be 0.18 * 0.35 * 22.5 = 1.4% of the GDP. And
these calculations still assume that a boycott against Catalan consumer
goods would be almost 10 times (60% vs. 6.5%) higher than the 2005
boycott against Catalan cava. In short, any reasonable scenario
indicates that the commercial effects of independence would have a
relatively small impact on the Catalan GDP, especially when compared to
the 8% fiscal dividend of independence."

2014
Various authors. Questions and Answers on The Economy of Catalonia. Questions and answers on the economic impact of independence. See Ch. 10, "Independence and Boycott", byXavier Cuadras Morató and Modest Guinjoan. Col·legi d’Economistes de Catalunya i Profit Editorial, Barcelona. http://www.coleconomistes.cat/pdf/the.economy.of.catalonia.pdf
Extract: "The figures presented in this article show that the reduction of exports
to Spain would have to be of a catastrophic and, consequently, totally
unthinkable magnitude in order for it to be able to cancel out the
positive fiscal benefits".